The subject matter disclosed herein relates to a system and method for a non-invasive blood pressure monitor. More specifically, the subject matter disclosed herein relates to a system and method for a non-invasive blood pressure monitor that is configured to more accurately estimate one or more blood pressure parameters.
Non-invasive blood pressure (NIBP) monitors typically inflate a pressure cuff above the patient's systolic pressure and measure very small amplitude pressure oscillations within the cuff as the cuff is deflated either in steps or continuously. The pressure oscillations in the cuff are due to volume oscillations resulting from the heart beating and pumping blood through the arterial system. The size of the cuff pressure oscillations changes as the cuff pressure itself changes. The data set which describes the cuff oscillation size as a function of the cuff pressure is commonly known as the oscillometric envelope. The resulting oscillometric envelope obtained from the cuff pressure data is used to determine the patient's blood pressure. The cuff pressure corresponding to the maximum oscillation amplitude is typically taken as the mean arterial pressure (MAP). Systolic and Diastolic pressures are computed by finding the cuff pressure levels at which a fixed ratio of the maximum oscillation amplitude occurs. Some NIBP monitors also use details in the shape of the oscillometric envelope to compute the Systolic and Diastolic pressures.
The cuff pressure data can, in some cases, contain various types of artifacts that may hinder the ability of the NIBP device to estimate blood pressure values accurately. Two primary classes of artifacts are patient motion and transient baseline effects. Conventional NIBP techniques are not capable of handling these artifact problems effectively and this can often introduce imprecision into the blood pressure estimates, and may also result in longer determination times which can be uncomfortable to the patient. Transient baseline effects are well known to those skilled in the art, and may include such phenomena as the heating and cooling of the air within the cuff, the visco-elastic effects of the cuff material which influence the time needed to reach pressure-volume equilibrium, and physiological changes in fluid and tissue volume under the cuff.